In the optical fiber art, lightguide fibers are used in optical transmission systems wherein the fibers are connected end-to-end to transfer light therebetween. The fibers usually are terminated in connectors which center tile fibers to provide low insertion losses. The connectors are coupled together so that their encapsulated fibers connect or abut end-to-end.
Optical fiber connectors often include a connector body, a forwardly projecting ferrule of ceramic or other rigid material, and a connecting member for coupling the connector to a complementary connector. The fiber projects slightly from the distal end of the ferrule.
Signal loss can be encountered because light is lost if the end faces of the connected fibers are separated at a gap or because light diverges as it radiates from one or both of the fibers. Consequently, it has become conventional and necessary to polish the end faces of the fibers which protrude beyond the connector ferrules prior to incorporation of the connectors into an optical fiber transmission system.
Various problems have been encountered for many years with optical fiber polishing tools or machines. For instance, when the end faces of fibers are polished over a relatively rigid polishing surface, the protruding fiber ends often become damaged or broken during polishing and often become over-polished which leaves little or no margin for error in establishing a good abutting relationship between opposing ends of a pair of mating fibers. It also has been found that transmission losses occur when the ends of the fibers are polished in a generally flat plane, because of gaps created when the flat end faces are not precisely parallel.
Consequently, attempts have been made to employ polishing surfaces which are backed by resilient material, such as a foam material, so that the polishing surface is resilient or yielding. Such "soft" polishing surfaces tend to lessen the previously encountered damage to or overpolishing of the fiber ends. In addition, such soft polishing surfaces create a convex polished end on an optical fiber so that a pair of abutting fibers are ensured to engage without a gap therebetween. However, such resilient or soft polishing surfaces have been inconsistent, the resilient materials, such as foam backings, tend to age and deteriorate, and the resulting polished fibers simply have not been totally acceptable.
This invention is directed to solving the above problems by providing an improved optical fiber polishing apparatus which has a yielding polishing surface to prevent damage to or breakage of the fiber ends, to prevent overpolishing of the fiber ends, and to provide a consistent medium to effect consistent convex polishing of the end faces of the fiber ends.